Ni-Mo Alloy Electrodeposited over Ni Substrate for HER on Water Electrolysis

Alkaline water electrolysis is a versatile technology for hydrogen production in situ. In this work, we study two different electrodeposited Ni-Mo alloys, with good electrocatalytic activity to hydrogen evolution reaction (HER). We propose Ni as substrate avoiding the corrosion and electrolyte contamination problem derived from eventual coating failure during long-term operations. The stable behavior of Ni as substrate as well as its known HER catalytic activity in alkaline electrolyzers make it attractive as a good option for our purpose. We prepare and characterize several Ni-Mo coatings over Ni by direct and pulse current supply electrodepositions. Ni-Mo coating prepared by pulse plating with a peak current density of 280mAcm(-2) and 35% duty cycle exhibited the best electrocatalytic activity for HER. The coating is an amorphous alloy whose XRD peaks correspond to an f.c.c. Ni structure, with Mo substituent atoms and a rough cauliflower-like microstructure, with Mo content of 23at.%. After 1000 cyclic voltammetry cycles, the electrocatalytic activity of the Ni-Mo electrocatalyst remains practically unchanged, and during 200h of H-2 evolution it maintains an overvoltage reduction of ca. 200mV compared with bare Ni.